U.S. patent application number 16/024163 was filed with the patent office on 2019-01-03 for apparatus and method for handover in wireless communication system.
The applicant listed for this patent is Korea University Research and Business Foundation, Samsung Electronics Co., Ltd.. Invention is credited to Young Kyo BAEK, Chung Gu Kang, Sunghoon Kim, Hoyeon Lee, Jun Man Lee, Jungje Son, Chan Seok Yang.
Application Number | 20190007879 16/024163 |
Document ID | / |
Family ID | 64734964 |
Filed Date | 2019-01-03 |
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United States Patent
Application |
20190007879 |
Kind Code |
A1 |
BAEK; Young Kyo ; et
al. |
January 3, 2019 |
APPARATUS AND METHOD FOR HANDOVER IN WIRELESS COMMUNICATION
SYSTEM
Abstract
The disclosure relates to a pre-5.sup.th-Generation (5G) or 5G
communication system to be provided for supporting higher data
rates Beyond 4.sup.th-Generation (4G) communication system such as
Long Term Evolution (LTE). a method for operating a terminal in a
wireless communication system is provided. The method includes
receiving information relating to a data session from a network
node, determining a target node among nodes belonging to a second
network based on the information relating to the data session, and
performing a handover from a source node belonging to a first
network to the target node.
Inventors: |
BAEK; Young Kyo; (Seoul,
KR) ; Kang; Chung Gu; (Seoul, KR) ; Yang; Chan
Seok; (Gyeonggi-do, KR) ; Son; Jungje;
(Gyeonggi-do, KR) ; Kim; Sunghoon; (Seoul, KR)
; Lee; Jun Man; (Jeollabuk-do, KR) ; Lee;
Hoyeon; (Seoul, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Samsung Electronics Co., Ltd.
Korea University Research and Business Foundation |
Gyeonggi-do
Seoul |
|
KR
KR |
|
|
Family ID: |
64734964 |
Appl. No.: |
16/024163 |
Filed: |
June 29, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 36/30 20130101;
H04W 36/14 20130101; H04W 36/0066 20130101; H04W 36/0061 20130101;
H04W 36/00835 20180801; H04W 36/0044 20130101 |
International
Class: |
H04W 36/14 20060101
H04W036/14; H04W 36/00 20060101 H04W036/00; H04W 36/30 20060101
H04W036/30 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 30, 2017 |
KR |
10-2017-0083718 |
Claims
1. A method for operating a terminal in a wireless communication
system, the method comprising: receiving information relating to a
data session from a network node; determining a target node among
nodes belonging to a second network, based on the information
relating to the data session; and performing a handover from a
source node belonging to a first network to the target node
belonging to the second network.
2. The method of claim 1, wherein the first network includes a
network using a licensed band, and the second network includes a
network using an unlicensed band.
3. The method of claim 1, wherein receiving the information
relating to the data session comprises receiving an identifier for
the data session, wireless quality relating to the data session, a
target node list for the second network, and a timer for triggering
of the handover.
4. The method of claim 1, wherein determining the target node
belonging to the second network comprises: determining wireless
quality relating to the data session, based on the information
relating to the data session; and determining the target node
belonging to the second network, based on the wireless quality.
5. The method of claim 1, wherein performing the handover from the
source node belonging to the first network to the target node
belonging to the second network comprises receiving, from the
network node, information for establishing the data session.
6. The method of claim 1, wherein performing the handover from the
source node belonging to the first network to the target node
belonging to the second network comprises: ceasing transmitting
data to the source node belonging to the first network, and wherein
information relating to a sequence number of other data, which has
been already transmitted from the terminal to the source node or
has been already transmitted from the source node to the terminal,
is transmitted from the source node to another network node.
7. A terminal in a wireless communication system, the terminal
comprising: at least one transceiver; and at least one processor
operably coupled to the at least one transceiver and configured to
receive information relating to a data session from a network node,
determine a target node belonging to a second network based on the
information relating to the data session, and perform a handover
from a source node belonging to a first network to the target node
belonging to the second network.
8. The terminal of claim 7, wherein the first network includes a
network using a licensed band, and the second network includes a
network using an unlicensed band.
9. The terminal of claim 7, wherein the at least one processor is
further configured to receive an identifier for the data session,
wireless quality relating to the data session, a target node list
for the second network, and a timer for triggering of the
handover.
10. The terminal of claim 7, wherein the at least one processor is
further configured to determine wireless quality relating to the
data session based on the information relating to the data session,
and determine the target node belonging to the second network based
on the wireless quality.
11. The terminal of claim 7, wherein the at least one processor is
further configured to receive, from the network node, information
for establishing the data session.
12. The terminal of claim 7, wherein the at least one processor is
further configured to cease transmitting data to the source node
belonging to the first network, and information relating to a
sequence number of other data, which has been already transmitted
from the terminal to the source node or has been already
transmitted from the source node to the terminal, is transmitted
from the source node to another network node.
13. A network node in a wireless communication system, the network
node comprising: at least one transceiver; and at least one
processor operably coupled to the at least one transceiver and
configured to perform transmission of information relating to a
data session to a terminal, and perform a handover from a source
node belonging to a first network to a target node belonging to a
second network in response to the transmission, and the information
relating to the data session is used to determine the target node
belonging to the second network.
14. The network node of claim 13, wherein the first network
includes a network using a licensed band, and the second network
includes a network using an unlicensed band.
15. The network node of claim 13, wherein the at least one
processor is further configured to: determine whether to trigger
the handover of the terminal based on at least one of a mobility
pattern of the terminal, information relating to at least one
target node belonging to the second network, information regarding
the data session for performing the handover of the terminal, and a
measurement value of the terminal; and transmit the information
relating to the data session to the terminal depending on the
determination.
16. The network node of claim 13, wherein the at least one
processor is further configured to transmit, to the terminal,
information for establishing the data session in response to the
transmission.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This application is based on and claims priority under 35
U.S.C. .sctn. 119(a) to Korean Patent Application Serial No.
10-2017-0083718, which was filed on Jun. 30, 2017 in the Korean
Intellectual Property Office, the entire disclosure of which is
incorporated herein by reference.
BACKGROUND
1. Field
[0002] The disclosure relates, generally, to a wireless
communication system, and more particularly, to an apparatus and
method for a handover in a wireless communication system.
2. Description of Related Art
[0003] To meet the demand for wireless data traffic having
increased since deployment of 4.sup.th generation (4G)
communication systems, efforts have been made to develop an
improved 5.sup.th generation (5G) or pre-5G communication system.
Therefore, the 5G or pre-5G communication system is also called a
`Beyond 4G Network` or a `Post Long Term Evolution (LTE)
System`.
[0004] The 5G communication system is considered to be implemented
in higher frequency (mm Wave) bands, e.g., 28 GHz or 60 GHz bands,
so as to accomplish higher data rates. To decrease propagation loss
of the radio waves and increase the transmission distance, the
beamforming, massive multiple-input multiple-output (MIMO), Full
Dimensional MIMO (FD-MIMO), array antenna, an analog beam forming,
large scale antenna techniques are discussed in 5G communication
systems.
[0005] In addition, in 5G communication systems, development for
system network improvement is under way based on advanced small
cells, cloud Radio Access Networks (RANs), ultra-dense networks,
device-to-device (D2D) communication, wireless backhaul, moving
network, cooperative communication, Coordinated Multi-Points
(CoMP), reception-end interference cancellation and the like.
[0006] In the 5G system, Hybrid frequency shift keying (FSK) and
quadrature amplitude modulation (FQAM) and sliding window
superposition coding (SWSC) as an advanced coding modulation (ACM),
and filter bank multi carrier (FBMC), non-orthogonal multiple
access (NOMA), and sparse code multiple access (SCMA) as an
advanced access technology have been developed.
[0007] In a 5G communication system, when a network through a
licensed band and a network through an unlicensed band coexist, a
detailed process for performing, by a terminal, a handover from a
source node belonging to the network through the licensed band to a
target node belonging to the network through the unlicensed band
has not yet been considered.
[0008] The above information is presented as background information
only to assist with an understanding of the present disclosure. No
determination has been made, and no assertion is made, as to
whether any of the above might be applicable as prior art with
regard to the present disclosure.
SUMMARY
[0009] The disclosure has been made to address at least the
disadvantages described above and to provide at least the
advantages described below. Accordingly, an aspect of the
disclosure provides an apparatus and method for triggering a
handover of a terminal by transmitting information relating to a
data session in a wireless communication system.
[0010] An aspect of the disclosure provides an apparatus and method
for determining a target node belonging to a second network on the
basis of information relating to a data session in a wireless
communication system.
[0011] An aspect of the disclosure provides an apparatus and method
for transmitting information for instructing data session
establishment in a wireless communication system.
[0012] An aspect of the disclosure provides an apparatus and method
for transmitting a sequence number for data which has yet to be
transmitted to a terminal in a wireless communication system.
[0013] In accordance with an aspect of the disclosure, there is
provided a method for operating a terminal in a wireless
communication system. The method includes receiving information
relating to a data session from a network node, determining a
target node among nodes belonging to a second network based on the
information relating to the data session, and performing a handover
from a source node belonging to a first network to the target
node.
[0014] In accordance with an aspect of the disclosure, there is
provided a method for operating a network node in a wireless
communication system. The method includes transmitting information
relating to a data session to a terminal and processing a handover
from a source node belonging to a first network to a target node
belonging to a second network in response to transmitting the
information relating to a data session, wherein the information
relating to the data session is used to determine the target node
belonging to the second network.
[0015] In accordance with an aspect of the disclosure, there is
provided a terminal in a wireless communication system. The
terminal includes at least one transceiver and at least one
processor operably coupled to the at least one transceiver and
configured to receive information relating to a data session from a
network node, determine a target node belonging to a second network
based on the information relating to the data session, and perform
a handover from a source node belonging to a first network to the
target node belonging to the second network.
[0016] In accordance with an aspect of the disclosure, there is
provided a network node in a wireless communication system. The
network node includes at least one transceiver and at least one
processor operably coupled to the at least one transceiver and
configured to perform transmission of information relating to a
data session to a terminal, and process a handover from a source
node belonging to a first network to a target node belonging to a
second network in response to the transmission, and the information
relating to the data session is used to determine the target node
belonging to the second network.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The above and other aspects, features and advantages of
certain embodiments of the disclosure will be more apparent from
the following detailed description taken in conjunction with the
accompanying drawings, in which:
[0018] FIG. 1 is a diagram of a wireless communication system,
according to an embodiment;
[0019] FIG. 2 is a diagram of a terminal in a wireless
communication system, according to an embodiment;
[0020] FIG. 3 is a diagram of an access and mobility management
node in a wireless communication system, according to an
embodiment;
[0021] FIG. 4 is a flowchart of a method that can be used by a
terminal in a wireless communication system, according to an
embodiment;
[0022] FIG. 5 is a flowchart of a method that can be used by an
access and mobility management node in a wireless communication
system, according to an embodiment;
[0023] FIG. 6 is a diagram of a signal exchange for a handover in a
wireless communication system, according to an embodiment;
[0024] FIG. 7 is a diagram of a signal exchange for a handover
preparation procedure in a wireless communication system, according
to an embodiment;
[0025] FIG. 8 is a diagram of a signal exchange for a handover
decision procedure in a wireless communication system, according to
an embodiment;
[0026] FIG. 9 is a diagram of a signal exchange for a handover
execution procedure in a wireless communication system, according
to an embodiment;
[0027] FIG. 10 is a diagram of a signal exchange for a handover
completion procedure in a wireless communication system, according
to an embodiment;
[0028] FIG. 11 is a diagram of a wireless communication system for
measuring performance in a wireless communication system, according
to an embodiment;
[0029] FIGS. 12A and 12B are diagrams of an arrangement of target
nodes belonging to a second network in a wireless communication
system, according to an embodiment;
[0030] FIGS. 13A to 13C are diagrams of a tracking area list (TAL)
for a second network in a wireless communication system, according
to an embodiment;
[0031] FIGS. 14A and 14B are diagrams of performance graphs
relative to a conventional scheme; and
[0032] FIGS. 15A and 15B are diagrams of performance graphs
according to a TAL in a wireless communication system, according to
an embodiment.
DETAILED DESCRIPTION
[0033] Embodiments of the disclosure will be described herein below
with reference to the accompanying drawings. However, the
embodiments of the disclosure are not limited to the specific
embodiments and should be construed as including all modifications,
changes, equivalent devices and methods, and/or alternative
embodiments of the present disclosure. In the description of the
drawings, similar reference numerals are used for similar
elements.
[0034] The terms "have," "may have," "include," and "may include"
as used herein indicate the presence of corresponding features (for
example, elements such as numerical values, functions, operations,
or parts), and do not preclude the presence of additional
features.
[0035] The terms "A or B," "at least one of A or/and B," or "one or
more of A or/and B" as used herein include all possible
combinations of items enumerated with them. For example, "A or B,"
"at least one of A and B," or "at least one of A or B" means (1)
including at least one A, (2) including at least one B, or (3)
including both at least one A and at least one B.
[0036] The terms such as "first" and "second" as used herein may
use corresponding components regardless of importance or an order
and are used to distinguish a component from another without
limiting the components. These terms may be used for the purpose of
distinguishing one element from another element. For example, a
first user device and a second user device may indicate different
user devices regardless of the order or importance. For example, a
first element may be referred to as a second element without
departing from the scope the disclosure, and similarly, a second
element may be referred to as a first element.
[0037] It will be understood that, when an element (for example, a
first element) is "(operatively or communicatively) coupled
with/to" or "connected to" another element (for example, a second
element), the element may be directly coupled with/to another
element, and there may be an intervening element (for example, a
third element) between the element and another element. To the
contrary, it will be understood that, when an element (for example,
a first element) is "directly coupled with/to" or "directly
connected to" another element (for example, a second element),
there is no intervening element (for example, a third element)
between the element and another element.
[0038] The expression "configured to (or set to)" as used herein
may be used interchangeably with "suitable for," "having the
capacity to," "designed to," "adapted to," "made to," or "capable
of" according to a context. The term "configured to (set to)" does
not necessarily mean "specifically designed to" in a hardware
level. Instead, the expression "apparatus configured to . . . " may
mean that the apparatus is "capable of . . . " along with other
devices or parts in a certain context. For example, "a processor
configured to (set to) perform A, B, and C" may mean a dedicated
processor (e.g., an embedded processor) for performing a
corresponding operation, or a generic-purpose processor (e.g., a
central processing unit (CPU) or an application processor (AP))
capable of performing a corresponding operation by executing one or
more software programs stored in a memory device.
[0039] The terms used in describing the various embodiments of the
disclosure are for the purpose of describing particular embodiments
and are not intended to limit the disclosure. As used herein, the
singular forms are intended to include the plural forms as well,
unless the context clearly indicates otherwise. All of the terms
used herein including technical or scientific terms have the same
meanings as those generally understood by an ordinary skilled
person in the related art unless they are defined otherwise. The
terms defined in a generally used dictionary should be interpreted
as having the same or similar meanings as the contextual meanings
of the relevant technology and should not be interpreted as having
ideal or exaggerated meanings unless they are clearly defined
herein. According to circumstances, even the terms defined in this
disclosure should not be interpreted as excluding the embodiments
of the disclosure.
[0040] The term "module" as used herein may, for example, mean a
unit including one of hardware, software, and firmware or a
combination of two or more of them. The "module" may be
interchangeably used with, for example, the term "unit", "logic",
"logical block", "component", or "circuit". The "module" may be a
minimum unit of an integrated component element or a part thereof.
The "module" may be a minimum unit for performing one or more
functions or a part thereof. The "module" may be mechanically or
electronically implemented. For example, the "module" according to
the disclosure may include at least one of an application-specific
integrated circuit (ASIC) chip, a field-programmable gate array
(FPGA), and a programmable-logic device for performing operations
which has been known or are to be developed hereinafter.
[0041] An electronic device according to the disclosure may include
at least one of, for example, a smart phone, a tablet personal
computer (PC), a mobile phone, a video phone, an electronic book
reader (e-book reader), a desktop PC, a laptop PC, a netbook
computer, a workstation, a server, a personal digital assistant
(PDA), a portable multimedia player (PMP), a MPEG-1 audio layer-3
(MP3) player, a mobile medical device, a camera, and a wearable
device. The wearable device may include at least one of an
accessory type (e.g., a watch, a ring, a bracelet, an anklet, a
necklace, a glasses, a contact lens, or a head-mounted device
(HMD)), a fabric or clothing integrated type (e.g., an electronic
clothing), a body-mounted type (e.g., a skin pad, or tattoo), and a
bio-implantable type (e.g., an implantable circuit).
[0042] The electronic device may be a home appliance. The home
appliance may include at least one of, for example, a television, a
digital video disk (DVD) player, an audio, a refrigerator, an air
conditioner, a vacuum cleaner, an oven, a microwave oven, a washing
machine, an air cleaner, a set-top box, a home automation control
panel, a security control panel, a TV box (e.g., Samsung
HomeSync.TM., Apple TV.TM., or Google TV.TM.), a game console
(e.g., Xbox.TM. and PlayStation.TM.), an electronic dictionary, an
electronic key, a camcorder, and an electronic photo frame.
[0043] The electronic device may include at least one of various
medical devices (e.g., various portable medical measuring devices
(a blood glucose monitoring device, a heart rate monitoring device,
a blood pressure measuring device, a body temperature measuring
device, etc.), a magnetic resonance angiography (MRA), a magnetic
resonance imaging (MRI), a computed tomography (CT) machine, and an
ultrasonic machine), a navigation device, a global positioning
system (GPS) receiver, an event data recorder (EDR), a flight data
recorder (FDR), a vehicle infotainment device, an electronic device
for a ship (e.g., a navigation device for a ship, and a
gyro-compass), avionics, security devices, an automotive head unit,
a robot for home or industry, an automatic teller machine (ATM) in
banks, point of sales (POS) devices in a shop, or an Internet of
things (IoT) device (e.g., a light bulb, various sensors, electric
or gas meter, a sprinkler device, a fire alarm, a thermostat, a
streetlamp, a toaster, a sporting goods, a hot water tank, a
heater, a boiler, etc.).
[0044] The electronic device may include at least one of a part of
furniture or a building/structure, an electronic board, an
electronic signature receiving device, a projector, and various
kinds of measuring instruments (e.g., a water meter, an electric
meter, a gas meter, and a radio wave meter). The electronic device
may be a combination of one or more of the aforementioned various
devices. The electronic device may also be a flexible device.
Further, the electronic device is not limited to the aforementioned
devices, and may include an electronic device according to the
development of new technology.
[0045] The embodiments described herein can be embodied using
either hardware or software, or both.
[0046] Hereinafter, an electronic device will be described with
reference to the accompanying drawings. In the disclosure, the term
"user" may indicate a person using an electronic device or a device
(e.g., an artificial intelligence electronic device) using an
electronic device.
[0047] The disclosure relates to an apparatus and method for a
handover in a wireless communication system. Specifically, in the
disclosure, a technology for performing a handover based on
information relating to a data session in a wireless communication
system is described.
[0048] Further, in the disclosure, even though various embodiments
are described using terms which have been used in certain
telecommunications standards (e.g., The 3rd Generation Partnership
Project (3GPP)), these terms are merely examples, and the
embodiments of the disclosure may be modified and applied to other
communication systems.
[0049] FIG. 1 is a diagram of a wireless communication system,
according to an embodiment. FIG. 1 illustrates, in a wireless
communication system, a terminal 110, a source node 120, a target
node 130, an access stop-off node 140, an access and mobility
management node 150, a session management node 160, a user plane
node 170, and a network 180. Although FIG. 1 illustrates only one
terminal 110, another terminal that is the same as or similar to
the terminal 110 may be further included.
[0050] The terminal 110 is a device that can be used by a user and
communicates with the source node 120 or the target node 130
through a wireless channel. In some cases, the terminal 110 may
operate without involvement of the user. That is, the terminal 110
may be an apparatus configured to perform machine type
communication (MTC) and may not be carried by the user. The
terminal 110 may also be referred to as a terminal, user equipment
(UE), a mobile station, a subscriber station, a remote terminal, a
wireless terminal, a user device, or another term having a
technical meaning equivalent thereto.
[0051] Each of the source node 120 and the target node 130 is a
network infrastructure configured to provide a wireless access to
the terminal 110. The source node 120 belongs to a first network
and may communicate with the terminal 110 through a first radio
access technology (RAT). The source node 120 may belong to a second
network, and the target node 130 belongs to the second network and
may communicate with the terminal 110 through a second RAT. The
first network may include a network using a licensed band, and the
first network may include a network using cellular communication.
For example, the first network may include a network using
long-term evolution (LTE) or 5G communication. The first network
may be referred to, depending on a technical meaning thereof, as a
3GPP network or another name having a technical meaning equivalent
thereto. The second network may include a network using an
unlicensed band, and the second network may include a network using
non-cellular communication. The second network may be trusted or
untrusted. The second network, which when it is trusted, may
include a second network having a high security level, and the
second network, which when it is untrusted, may include a second
network having a low security level. The second network may include
a network using wireless fidelity (Wi-Fi). The second network may
be referred to, depending on a technical meaning thereof, as a
non-3GPP network or another name having a technical meaning
equivalent thereto. The source node 120 and the target node 130 can
have coverage defined in a predetermined geographical area based on
a distance to which a signal can be transmitted. The source node
120 and the target node 130 may be referred to as a base station,
an access point (AP), an eNodeB (eNB), a 5.sup.th Generation (5G)
node, a wireless point, a transmission/reception Point (TRP), or
another term having a technical meaning equivalent thereto.
[0052] The access stop-off node 140 allows the terminal 110 to have
access to a core network through the second network. The core
network may include the access and mobility management node 150 and
the user plane node 170. The access stop-off node 140 may belong to
a public land mobile Network (PLMN), which can be the same as the
source node 120. The access stop-off node 140 may be referred to as
a non-3GPP interworking function (N3IWF) or another name having a
technical meaning equivalent thereto.
[0053] The access and mobility management node 150 manages a
network access and mobility of the terminal 110. When both the
source node 120 and the target node 130 are connected to the access
and mobility management node 150, the access and mobility
management node 150 may manage a handover of the terminal 110 from
the source node 120 to the target node 130. The access and mobility
management node 150 may be referred to as an access and mobility
management function (AMF) or another name having a technical
meaning equivalent thereto.
[0054] The session management node 160 manages a data session
between the terminal 110 and the source node 120 or the target node
130. The session management node 160 may select the user plane node
170 for a corresponding data session. The session management node
160 may be referred to as a session management function (SMF) or
another name having a technical meaning equivalent thereto.
[0055] The user plane node 170 functions as an anchor of an
internet protocol (IP). The user plane node 170 may be referred to
as a user plane function (UPF) or another name having a technical
meaning equivalent thereto.
[0056] The network 180 transfers data using a downlink to the user
plane node 170. The network 180 receives data transmitted by the
terminal 110 from the user plane node 170.
[0057] Although each of the terminal 110, the source node 120, the
target node 130, the access stop-off node 140, the access and
mobility management node 150, the session management node 160, the
user plane node 170, and the network 180 as one node in FIG. 1, one
or more nodes may be implemented as one node. In addition, the
terminal 110, the source node 120, the target node 130, the access
stop-off node 140, the access and mobility management node 150, the
session management node 160, the user plane node 170, and the
network 180 may be configured by hardware or software and, for
example, may configure a network configured through software such
as software defined networking (SDN).
[0058] FIG. 2 is a diagram of a terminal in a wireless
communication system, according to an embodiment. The configuration
of FIG. 2 may be used in the terminal 110.
[0059] Referring to FIG. 2, the terminal 110 includes a
communication unit 210, a storage unit, and a control unit 230, and
one or more antennas.
[0060] The communication unit 210 transmits and/or receives a
signal through a wireless channel. The communication unit 210
converts between a baseband signal and a bitstream based on a
physical layer standard of a system. When data is transmitted, the
communication unit 210 generates complex-valued symbols by encoding
and modulating a transmission bitstream. When data is received, the
communication unit 210 restores a reception bitstream through
decoding and demodulation of a baseband signal. The communication
unit 210 up-converts a baseband signal into an RF band signal and
then transmits the converted signal through an antenna, and
down-converts an RF band signal received through the antenna into a
baseband signal. The communication unit 210 may include a
transmission filter, a reception filter, an amplifier, a mixer, an
oscillator, a digital to analog converter (DAC), an analog to
digital converter (ADC), etc.
[0061] The communication unit 210 may include multiple
transmission/reception paths. The communication unit 210 may
include at least one antenna array configured by multiple antenna
elements. The communication unit 310 may be configured by a digital
circuit and an analog circuit (e.g., a radio frequency integrated
circuit (RFIC)). The digital circuit and the analog circuit may be
implemented as a single package, a system on chip (SoC), an
integrated circuit (IC), etc. The communication unit 210 may
include multiple RF chains. In addition, the communication unit 210
may perform beamforming.
[0062] The communication unit 210 may include communication modules
different from one another in order to process signals at frequency
bands different from one another. The communication unit 210 may
include multiple communication modules in order to support multiple
wireless access technologies different from one another. The
wireless access technologies may include bluetooth (BT) low energy
(BLE), Wi-Fi, Wi-Fi Gigabyte (WiGig), a cellular network (e.g., 5G,
new radio (NR), and LTE), etc. The frequency bands may include a
super high frequency (SHF) band (e.g., 2.5 GHz and 5 GHz) and a
millimeter Wave (mmWave) band (e.g., 60 GHz).
[0063] The communication unit 210 transmits and receives a signal
as described above. Accordingly, all or a part of the communication
unit 210 may be referred to as a transmitter, a receiver, or a
transceiver.
[0064] The storage unit 220 stores data, such as a basic program,
an application program, configuration information, etc., for
operation of the terminal 110. The storage unit 220 may be
configured by a volatile memory, a non-volatile memory, or a
combination thereof. Further, the storage unit 220 provide data
stored at a request of the control unit 230.
[0065] The control unit 230 controls general operations of the
terminal 110. The control unit 230 transmits and receives a signal
through the communication unit 210. The control unit 230 records
data on the storage unit 220 and reads data from the storage unit
220. The control unit 230 may perform functions of a protocol stack
required for a communication standard. The control unit 230 may
include at least one processor or microprocessor or may be a part
of a processor. The control unit 230 and a part of the
communication unit 210 may be referred to as a communication
processor (CP).
[0066] The control unit 230 may control the terminal 110 to perform
a handover between networks that are different from each other.
Specifically, the control unit 230 may determine whether there is a
handover from the source node 120 belonging to the first network to
a target node 130 belonging to the second network, select the
target node 130 among nodes belonging to the second network on the
basis of information relating to a data session, and control
functions required for the handover to the target node 130. The
control unit 230 may control the terminal 110 to perform the
operations described in greater detail below.
[0067] FIG. 3 is a diagram of an access and mobility management
node in a wireless communication system, according to an
embodiment.
[0068] As illustrated in FIG. 3, the access and mobility management
node includes a communication unit 310, a storage unit 320, and a
control unit 330. The configuration shown in FIG. 3 may be used in
the access and mobility management node 150.
[0069] The communication unit 310 provides an interface for
communicating with other nodes in a network. The communication unit
310 converts a bitstream which is transmitted from the access and
mobility management node to another node into a physical signal,
and converts a physical signal received from another node into a
bitstream. The communication unit 310 may transmit and receive a
signal. Accordingly, the communication unit 310 may be referred to
as a transmitter, a receiver, or a transceiver.
[0070] The storage unit 320 stores data, such as a basic program,
an application program, configuration information, etc., for
operation of an upper node. The storage unit 320 provides data
stored at a request of the control unit 330.
[0071] The control unit 330 controls general operations of the
upper node. The control unit 330 transmits or receives a signal
through the communication unit 310. The control unit 330 records
data on the storage unit 320 and reads data from the storage unit
320. The control unit 330 may include a handover triggering
determination unit 332 that is configured to trigger a handover of
the terminal 110 and trigger data session establishment of the
terminal 110. The handover triggering determination unit 332 is an
instruction set or code stored in the storage unit 320, and may be
an instruction/code at least temporarily residing in the control
unit 330, a storage space storing the instruction/code, or a part
of circuitry configuring the control unit 330. The control unit 340
may control the access and mobility management node to perform
operations described in greater detail below.
[0072] FIG. 4 is a flowchart of a method used that can be used by
the terminal 110 in a wireless communication system, according to
an embodiment.
[0073] In step 401, the terminal 110 receives information relating
to a data session from the access and mobility management node 150.
Through a handover preparation procedure, the terminal 110 may
receive information relating to a data session and including an
identifier for the data session, wireless quality (e.g., quality of
service (QoS)) relating to the data session, a target node list for
the second network around the terminal 110, and a timer for
triggering a handover.
[0074] In step 403, the terminal 110 determines a target node 130
belonging to the second network based on the information relating
to the data session. Through a handover decision procedure, the
terminal 110 may identify wireless quality relating to a data
session on the basis of information relating to the data session
and may determine a target node 130 belonging to the second network
based on the wireless quality relating to the data session.
[0075] In step 405, the terminal 110 performs a handover from the
source node 120 belonging to the first network to the target node
130 belonging to the second network. Through a handover execution
procedure, the terminal 110 may receive, from the access and
mobility management node 150, information for instructing data
session establishment. Through a handover completion procedure, the
terminal 110 may cease transmitting data to the source node 120
belonging to the first network. Information relating to a sequence
number of data which has been already transmitted from the terminal
110 to the source node 120 belonging to the first network or has
been already transmitted from the source node 120 belonging to the
first network to the terminal 110 may be transmitted from the
source node 120 belonging to the first network to the user plane
node 170.
[0076] FIG. 5 is a flowchart of a method that can be used by an
access and mobility management node in a wireless communication
system, according to an embodiment.
[0077] In step 501, the access and mobility management node 150
transmits information relating to a data session to the terminal
110. Through the handover preparation procedure, the access and
mobility management node 150 may determine to trigger a handover of
the terminal 110 based on at least one among a mobility pattern of
the terminal 110, information relating to at least one target node
around the terminal 110, information regarding a data session for
the handover of the terminal 110, and a measurement value of the
terminal 110 and may transmit the information relating to the data
session.
[0078] In step 503, the access and mobility management node 150 may
process a handover of the terminal 110 from the source node 120
belonging to the first network to the target node 130 belonging to
the second network. Through the handover execution procedure, the
access and mobility management node 150 may transmit to the
terminal 110 information for instructing data session
establishment.
[0079] FIG. 6 is a diagram of a signal exchange for a handover in a
wireless communication system, according to an embodiment.
[0080] In step 601, the terminal 110 performs the handover
preparation procedure together with other nodes included in a
wireless communication system. The access and mobility management
node 150 may determine to trigger a handover of the terminal 110.
Subsequently, the access and mobility management node 150 may
transmit a handover triggering request to the terminal 110. The
handover preparation procedure may be performed under the lead of
the access and mobility management node 150, regardless of the type
of source node to which the terminal 110 has been connected and the
target node to which the terminal 110 is to perform a handover. The
handover preparation procedure may be performed under the lead of
the access and mobility management node 150, regardless of whether
the source node to which the terminal 110 has been connected at the
moment and the target node to which the terminal 110 is to perform
a handover belong to the first network or to the second network.
Details of the handover preparation procedure of step 601 will be
described in greater detail with respect to FIG. 7 below.
[0081] In step 603, the terminal 110 performs the handover decision
procedure together with other nodes included in a wireless
communication system. The terminal 110 may perform a procedure of
searching for a target node 130 belonging to the second network.
The terminal 110 may determine whether to perform a handover to the
discovered target node 130 belonging to the second network. If the
terminal 110 is not registered with the target node 130 belonging
to the second network, the terminal 110 may additionally perform a
target node registration procedure. The terminal 110 may transmit a
handover triggering response, to the access and mobility management
node 150. Details of the handover decision procedure of step 603
will be described in greater detail with respect to FIG. 8
below.
[0082] In step 605, the terminal 110 performs the handover
execution procedure together with other nodes included in a
wireless communication system. The terminal 110 may receive a
request to instruct to trigger data session establishment from the
access and mobility management node 150. The terminal 110 may
transmit a request for the data session establishment to the access
and mobility management node 150 in response to receiving of the
request. The data session may be referred to as a protocol data
unit (PDU) session. A PDU may signify a carrier (e.g., a packet
frame) including control information and data. Details of the
handover execution procedure of step 605 will be described in
greater detail with respect to FIG. 9 below.
[0083] In step 607, the terminal 110 performs the handover
completion procedure together with other nodes included in a
wireless communication system. The terminal 110 may perform a
procedure of data session establishment with a target node 130
belonging to the second network. The terminal 110 may receive
information of accepting the data session establishment with the
target node 130 belonging to the second network from the access and
mobility management node 150. The terminal 110 may cease data
transmission to the source node 120 belonging to the first network
and may complete the data session establishment with the target
node 130 belonging to the second network. The session management
node 160 may transmit a data forwarding request to the user plane
node 170. The data forwarding request may include a request to
forward data which has yet to be transmitted to the terminal 110.
The user plane node 170 may transmit to the source node 120
belonging to the first network an end marker to instruct to cease
data transmission to the terminal 110. In response thereto, the
source node 120 belonging to the first network may transmit a data
forwarding response to the user plane node 170. The data forwarding
response may include data which has yet to be transmitted to the
terminal 110. The terminal 110 may receive data having yet to be
received from the user plane node 170 and may complete a data
session with the source node 120 belonging to the first network.
Details of the handover completion procedure of step 607 will be
described in greater detail with respect to FIG. 10 below.
[0084] FIG. 7 is a diagram of a signal exchange for a handover
preparation procedure in a wireless communication system, according
to an embodiment.
[0085] Referring to FIG. 7, in step 701, the access and mobility
management node 150 determines to trigger a handover of the
terminal 110. The access and mobility management node 150 may
determine whether to trigger a handover of the terminal 110 based
on at least one parameter in Table 1 described below.
TABLE-US-00001 TABLE 1 Information Specific parameters of
information Obtain method Mobility pattern Movement speed of the
terminal 100 Obtainable periodically or by the access and mobility
management node 150 An amount of power remaining in the terminal
triggering a mobility pattern update procedure of the terminal. 110
Obtainable by the terminal 110 updating a mobility pattern
autonomously. An amount of data consumption through a licensed band
A tracking area to which the terminal belongs Target node belonging
Whether there is, around the terminal 110, a Obtainable through an
interface (e.g., N2) between the access and mobility to second
network target node belonging to the second network management node
150 and the access stop-off node 140. around the terminal connected
to the access and mobility When the second network is an untrusted
network, the access and mobility 110 management node 150 identical
to that of the management node 150 may not obtain information
relating to the target source node 120 belonging to the first
network. node belonging to the second network. An amount of traffic
load of the target node Before handover triggering, admission
control may be performed by belonging to the second network
connected to identifying an amount of traffic load of the target
node belonging to the the access and mobility management node 150
second network. For example, when traffic load of target nodes
belonging identical to that of the source node 120 to all the
second networks around the terminal 110 is greater than a belonging
to the first network. threshold value, the handover triggering may
not performed. Tracking Area List (TAL) Information relating The
access and mobility management node 150 may assign a TAL relating
to the second network assigned to the terminal to the second
network to the terminal 110. 110 The access and mobility management
node 150 may provide the terminal 110 with a handover policy by a
unit of TAL relating to the second network assigned to the terminal
110. That is, whenever the TAL relating to the second network
assigned to the terminal 110 is changed, the access and mobility
management node 150 may provide a handover policy updated through a
handover triggering request. Handover performance differs depending
on what TAL is assigned to the terminal 110 and what handover
policy is provided in response to the assigned TAL. Information
relating QoS profile (Guaranteed Bit Rate (GBR)/non- Obtainable
through an interface (e.g., N11) between the access and mobility to
PDU session for GBR) management node 150 and the session management
node 160 performing handover Measurement A measurement event due to
a signal strength Obtainable from the terminal 110 when a
predetermined event occurs while information relating to An amount
of traffic load of the source node the terminal 110 periodically
measures a signal strength of a neighbouring terminal 110 120
belonging to the first network cell.
[0086] When a parameter value for a mobility pattern of the
terminal 110 is greater than a threshold value, the access and
mobility management node 150 may determine to trigger a handover of
the terminal 110. When an amount of traffic load of the target node
130 belonging to the second network is less or smaller than a
threshold value, the access and mobility management node 150 may
determine to trigger a handover of the terminal 110. When a
parameter value for a QoS profile is greater than a threshold
value, the access and mobility management node 150 may determine to
trigger a handover of the terminal 110. The access and mobility
management node 150 may determine to trigger a handover of the
terminal 110 from a predetermined event or at a predetermined time.
When the access and mobility management node 150 determines not to
trigger any handover of the terminal 110, a connection to the
source node 120 belonging to the first network may be maintained,
and step 701 may be performed again after a predetermined time has
elapsed. The access and mobility management node 150 may determine
a handover policy for the terminal 110 by using a mobility pattern
of the terminal 110 and information relating to the target node
belonging to the second network around the terminal 110.
[0087] In step 703, the access and mobility management node 150
transmits a handover triggering request to the terminal 110. The
handover triggering request may be transmitted to the terminal 110
through the source node 120 belonging to the first network. The
handover triggering request may include at least partial
information in Table 2 described below.
TABLE-US-00002 TABLE 2 Required or Information optional Use Note
Identifier for PDU Required The terminal 110 may provide an When
the identifier for the PDU session is not session identifier for a
PDU session in order transmitted, a handover may be performed for
all PDU for the terminal 110 to perform a sessions. handover. QoS
profile for each Required The terminal 110 may provide The access
and mobility management node 150 may PDU Session essential
information for transmit, to the terminal 110, a QoS profile for
each PDU determination of a handover. session received from the
session management node 160. Target node list for Optional An
amount of traffic load of searching The target node list may
include a handover priority order second network for a target node
belonging to the for target nodes belonging to the second network
in the second network around the terminal target node list. 110 may
be reduced. Target nodes belonging to the second network in the
Admission control for the target node target node list may be
connected to the access and belonging to the second network may
mobility management node 150 identical to that of the be performed.
source node 120 belonging to the first network. The target node
list may be determined on the basis of a mobility pattern of the
terminal 110, a target node belonging to the second network around
the terminal 110, information relating to a PDU session for
performing a handover, and measurement information relating to the
terminal 110. The access and mobility management node 150 may
instruct the terminal 110 to select only a target node belonging to
the second network in the target node list, and may perform the
admission control. Timer for handover Optional The terminal 110 may
be informed of The timer for handover triggering may be used to
limit a triggering a time during which information time elapsing
from the handover triggering until included in a handover
triggering determination of a handover of the terminal 110. request
is effective.
[0088] The access and mobility management node 150 provides the
terminal 110 with a handover policy determined by using a mobility
pattern of the terminal 110 and information relating to the target
node belonging to the second network around the terminal 110,
thereby guaranteeing a data session QoS budget and minimizing
performance degradation due to a handover. The handover policy may
include a target node list for the second network.
[0089] FIG. 8 is a diagram of a signal exchange for a handover
decision procedure in a wireless communication system, according to
an embodiment.
[0090] In step 801, the terminal 110 performs a procedure of
searching for a target node 130 belonging to the second network.
When the terminal 110 receives a target node list for the second
network from the access and mobility management node 150, the
terminal 110 may search for the target node 130 belonging to the
second network by using the target node list for the second
network. A target node list for the second network is provided,
thereby allowing reduction of a time that the terminal 110 spends
to search for the target node 130 belonging to the second network,
and allowing reduction of power consumption of the terminal 110.
The access and mobility management node 150 provides the target
node list for the second network, and an optimal handover policy
may thus be transferred to the terminal 110. When the terminal 110
does not receive a target node list for the second network from the
access and mobility management node 150, the terminal 110 may
search for all target nodes belonging to the second network
therearound. The terminal 110 may determine whether there is the
access stop-off node 140 and determine whether the source node 120
belonging to the first network and the access stop-off node 140 use
the same access and mobility management node 150 or PLMN.
[0091] In step 803, the terminal 110 determines whether to perform
a handover to the discovered target node 130 belonging to the
second network. The terminal 110 may determine whether to perform a
handover for each of the PDU session identifiers through the target
node 130 belonging to the second network. The terminal 110 may
identify wireless quality relating to the target node 130 belonging
to the second network to determine whether QoS relating to the PDU
session for performing a handover satisfies a predetermined
criterion. Wireless quality relating to the target node 130
belonging to the second network may include a wireless channel
access delay time, a signal strength, and a signal to interference
plus noise ratio (SINR). The terminal 110 may determine whether to
perform a handover to the target node 130 belonging to the second
network based on the information included in a handover triggering
request and the wireless quality relating to the target node
belonging to the second network. The terminal 110 may display a
user interface (UI) for finally inquiring of a user whether to
perform a handover to the target node 130 belonging to the second
network. The terminal 110 may determine to perform the handover to
the target node 130 belonging to the second network only when a
user input permitting the handover to the target node 130 belonging
to the second network has been received.
[0092] In step 805, when the terminal 110 is not registered with
the target node 130 belonging to the second network, the terminal
110 may additionally perform a target node registration procedure.
The terminal 110 may be registered with the target node 130
belonging to the second network, by transmitting a target node
registration request to the access and mobility management node 150
through the access stop-off node 140. When the terminal 110 is
registered with the target node 130 belonging to the second
network, step 805 may be omitted.
[0093] In step 807, the terminal 110 transmits a handover
triggering response to the access and mobility management node 150.
The handover triggering response may be transmitted to the access
and mobility management node 150 through the source node 120
belonging to the first network. The handover triggering response
may include an identifier of a PDU session. When the terminal 110
has determined not to perform a handover to the target node 130
belonging to the second network in step 803, the handover
triggering response may include a negative acknowledgement (NACK)
relating to the handover. The access and mobility management node
150, which has received the handover triggering response including
the NACK relating to the handover, may perform step 701 of FIG. 7
again.
[0094] FIG. 9 is a diagram of a signal exchange for a handover
execution procedure in a wireless communication system, according
to an embodiment.
[0095] In step 901, the terminal 110 receives from the access and
mobility management node 150 a request for instructing to trigger
PDU session establishment. The terminal 110 may perform a PDU
session establishment procedure only after receiving the request
for instructing to trigger PDU session establishment.
[0096] In step 903, the terminal 110 transmits a request for PDU
session establishment to the access and mobility management node
150 in response to receiving of the request. The terminal 110 can
inform the access and mobility management node 150 of handover
performance by configuring the type of a request for PDU session
establishment as "PDU session already exists". Transmitting a
request for establishing a PDU session, even though a PDU session
already exists, signifies performing a handover from the existing
PDU session to the other PDU session.
[0097] FIG. 10 is a diagram of a signal exchange for a handover
completion procedure in a wireless communication system, according
to an embodiment.
[0098] Referring to FIG. 10, in step 1001, the terminal 110
performs a procedure of PDU session establishment with the target
node 130 belonging to the second network. The terminal 110 may
generate a QoS flow of a PDU session with the access stop-off node
140. The QoS flow of the PDU session may include an internet
protocol security (IPsec) child security association (SA).
[0099] In step 1003, the terminal 110 receives from the access and
mobility management node 150 information of accepting the PDU
session establishment with the target node 130 belonging to the
second network. The information of accepting PDU session
establishment may include an identifier of the PDU session and a
QoS profile of the PDU session.
[0100] In step 1005, the terminal 110 ceases data transmission to
the source node 120 belonging to the first network. The terminal
110 may start data transmission to a target node 130 belonging to
the second network.
[0101] In step 1007, the access and mobility management node 150
completes the PDU session establishment through the target node 130
belonging to the second network. The access and mobility management
node 150 may transmit a session management request to the session
management node 160 and may receive a response relating thereto
from the session management node 160. The session management
request may include an interface (e.g., N2) between the access and
mobility management node 150 and the session management node 160.
The session management node 160 may transmit a session change
request to the user plane node 170 and may receive a response
relating thereto from the user plane node 170. The session change
request may include information for requesting to change an
interface (e.g., N4) between the session management node 160 and
the user plane node 170.
[0102] In step 1009, the session management node 160 transmits a
data forwarding request to the user plane node 170. The session
management node 160 may instruct the user plane node 170 to start a
data forwarding procedure. The data forwarding request may include
an identifier for the source node 120 belonging to the first
network and an identifier for a PDU session.
[0103] In step 1011, the user plane node 170 transmits an end
marker to the source node 120 belonging to the first network. The
end marker may include information for instructing to cease data
transmission to the terminal 110.
[0104] In step 1013, the source node 120 belonging to the first
network transmits a data forwarding response to the user plane node
170. The data forwarding response may include a sequence number of
data which has been already transmitted from the terminal 110 to
the source node 120 belonging to the first network, a sequence
number of data which has been already transmitted from the source
node 120 belonging to the first network to the terminal 110, and
data which has yet to be transmitted to the terminal 110. The
sequence number of data, which has been already transmitted from
the terminal 110 to the source node 120 belonging to the first
network, may include a sequence number of an uplink packet data
convergence protocol (PDCP). The sequence number of data, which has
been already transmitted from the source node 120 belonging to the
first network to the terminal 110, may include a sequence number of
a downlink PDCP.
[0105] In step 1015, the terminal 110 receives data which has yet
to be received from the user plane node 170. The terminal 110 may
receive the data, which the terminal 110 has yet to receive,
through the access stop-off node 140. Data which has yet to be
transmitted to the terminal 110 is forwarded and thus data
transmission delay due to data loss may be reduced.
[0106] In step 1017, the terminal 110 ends the PDU session with the
source node 120 belonging to the first network. The terminal 110
may complete the handover to the target node 130 belonging to the
second network, by ending the PDU session with the source node 120
belonging to the first network.
[0107] FIG. 11 is a diagram of a wireless communication system for
measuring performance in a wireless communication system, according
to an embodiment.
[0108] In the coverage of a single source node belonging to a first
network connected to an access and mobility management node 150,
multiple target nodes (e.g., target node 1101 and target node 1103)
belonging to a second network may exist. A target node 1101 may be
connected to the access and mobility management node 150 and a
target node 1103 may not be connected to the access and mobility
management node 150.
[0109] When the terminal 110 is located in an office, the access
and mobility management node 150 may provide a handover policy to
the terminal 110 by transmitting a handover triggering request. The
handover policy may include a target node list for the second
network. In this case, the target node 1101 belonging to the second
network included in the target node list for the second network may
be applied to a TAL for the second network assigned to the terminal
110. When the terminal 110 escapes from the TAL for the second
network assigned thereto, the access and mobility management node
150 may provide a new target node list to the terminal 110, and a
target node belonging to the second network included in the new
target node list may be applied to the TAL for the second network
assigned to the terminal 110. The access and mobility management
node 150 generates a target node list by inserting into the target
node list only a target node belonging to the second network
connected to the access and mobility management node 150, thereby
guaranteeing continuity of a data session (e.g., a PDU session)
when the terminal 110 performs a handover. The terminal 110 may
perform through the handover policy the handover to a target node
satisfying a predetermined condition among target nodes included in
the target node list for the second network.
[0110] FIGS. 12A and 12B are diagrams of an arrangement of target
nodes belonging to a second network in a wireless communication
system, according to an embodiment. Target nodes 1101 belonging to
the second network connected to the access and mobility management
node 150 and target nodes 1103 belonging to the second network not
connected to the access and mobility management node 150 are
arranged alternately.
[0111] Referring to FIG. 12A, 25 target nodes belonging to the
second network may be densely arranged in an office. The 25 target
nodes belonging to the second network may be uniformly spaced at 2
m intervals. The terminal 110 may perform a handover from a source
node belonging to the first network to a target node 1101 belonging
to the second network.
[0112] Referring to FIG. 12B, 25 target nodes belonging to the
second network may be sparsely arranged in an office. The 25 target
nodes belonging to the second network may be uniformly spaced at 5
m intervals. The terminal 110 may perform a handover from a source
node belonging to the first network to a target node 1101 belonging
to the second network. Penetration loss of 30 dB may be applied to
the target nodes belonging to the second network.
[0113] FIGS. 13A, 13B, and 13C are diagrams of a TAL for a second
network in a wireless communication system, according to an
embodiment.
[0114] Some of target nodes belonging to the second network
connected to the access and mobility management node 150 in an
office are assigned to TAL-1 1301, TAL-2 1303, and TAL-3 1305,
respectively. As in FIG. 13A, four target nodes 1311 belonging to
the second network may be assigned to TAL-1 1301. As in FIG. 13B,
nine target nodes 1313 belonging to the second network may be
assigned to TAL-2 1303. As in FIG. 13C, 13 target nodes 1315
belonging to the second network may be assigned to TAL-3 1305. When
TAL-3 1305 is assigned to the terminal 110, the terminal 110 is
made to perform handovers more frequently than when TAL-1 1301 is
assigned thereto, yet a better Signal to Noise Ratio (SNR) may be
provided. The more the target nodes belonging to the second network
are included in a TAL allocated to the terminal 110, the more
frequently the terminal 110 performs handovers, yet the better the
SNR provided thereto may be.
[0115] FIGS. 14A and 14B are diagrams of performance graphs
relative to a conventional scheme, according to an embodiment.
FIGS. 14A and 14B illustrate performance graphs relative to a
conventional technique when target nodes belonging to the second
network are densely arranged, and a terminal 110 to which TAL-1
1301 is assigned moves at 3 km/hour.
[0116] The conventional technique may not guarantee data session
continuity since the terminal 110 performs a handover to a target
node 1103 belonging to the second network not connected to the
access and mobility management node 150. Therefore, in the
conventional technique, a handover delay time may be increased, and
throughput may be reduced. By contrast, the technique according to
the disclosure may guarantee data session continuity since the
terminal 110 performs a handover only to a target node 1101
belonging to the second network connected to the access and
mobility management node 150. Therefore, the technique according to
the disclosure may have a shorter handover delay time and greater
throughput than those of the conventional technique. The
conventional technique may have a handover delay time of 1600 ms,
whereas the technique according to various embodiments of the
present disclosure may have a handover delay time of 66 ms. The
conventional technique may have throughput of 8.05 Mbps, whereas
the technique according to various embodiments of the disclosure
may have throughput of 14.78 Mbps.
[0117] FIGS. 15A and 15B are diagrams of performance graphs
according to a TAL in a wireless communication system, according to
an embodiment. FIGS. 15A and 15B illustrate performance graphs
where, when target nodes belonging to the second network are
sparsely arranged, a terminal 110 moves at 3 km/hour or 15 km/hour
and uses TAL-1 1301 or TAL-3 1305, respectively.
[0118] The number of handovers per minute performed when the
terminal 110 uses TAL-3 1305 may be greater than that performed
when the terminal 110 uses TAL-1 1301, regardless of the movement
speeds of the terminal 110. Overhead due to handovers performed
when the terminal 110 uses TAL-3 1305 may be more greatly increased
than when the terminal 110 uses TAL-1 1301.
[0119] Referring to FIG. 15B, the terminal 110 may have more
increased throughput when the terminal 110 uses TAL-3 1305 than
when the terminal 110 uses TAL-1 1301, regardless of the movement
speeds of the terminal 100. In general, the greater the overhead
due to handovers is increased, the more the throughput is reduced.
However, in the environment of FIGS. 15A and 15B, an SNR may more
greatly influence the throughput than the overhead due to
handovers. Therefore, the access and mobility management node 150
may provide an optimal target node list for the second network
according to a mobility pattern of the terminal 110.
[0120] The apparatuses and methods described herein can provide a
handover policy to a terminal by using a mobility pattern of the
terminal and information relating to target nodes belonging to a
second network around the terminal, so as to guarantee a data
session QoS budget, and minimize performance degradation due to the
handover.
[0121] The apparatuses and methods described herein can determine a
target node belonging to a second network based on the information
relating to a data session so as to allow reduction of a time that
a terminal spends to search for the target node belonging to the
second network and reduction of power consumption of the
terminal.
[0122] The apparatuses and methods described herein can transmit
information for instructing data session establishment in a
wireless communication system so as to allow a procedure of data
session establishment of a terminal to be triggered.
[0123] The apparatuses and methods described herein can transmit,
to a terminal, a sequence number for data having yet to be
transmitted, so as to enable reduction of a data transmission delay
due to a data loss.
[0124] When the methods described herein are implemented by
software, a non-transitory computer-readable storage medium for
storing one or more programs (software modules) may be provided.
The one or more programs stored in the non-transitory
computer-readable storage medium may be configured for execution by
one or more processors within the electronic device.
[0125] The programs (software modules or software) may be stored in
non-volatile memories including a random access memory (RAM) and a
flash memory, a read only memory (ROM), an electrically erasable
programmable ROM (EEPROM), a magnetic disc storage device, a
compact disc-ROM (CD-ROM), digital versatile discs (DVDs), or other
type optical storage devices, or a magnetic cassette.
Alternatively, any combination of some or all of the above may form
a memory in which the program is stored. Further, a plurality of
such memories may be included in the electronic device.
[0126] In addition, the programs may be stored in an attachable
storage device which is accessible through communication networks
such as the Internet, Intranet, local area network (LAN), wide area
network (WAN), and storage area network (SAN), or a combination
thereof. Such a storage device may access the electronic device via
an external port. Further, a separate storage device on the
communication network may access a portable electronic device.
[0127] While the disclosure has been shown and described with
reference to certain embodiments thereof, it will be understood by
those skilled in the art that various changes in form and details
may be made therein without departing from the scope of the
disclosure. Therefore, the scope of the disclosure should not be
defined as being limited to the embodiments, but should be defined
by the appended claims and equivalents thereof.
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